The concept of using biomass-derived materials to produce other useful products has been explored since man first used plant materials and animal fur to make clothing and tools. Biomass derived materials have also been used for centuries as adhesives, solvents, lighting materials, fuels, inks/paints/coatings, colorants, perfumes and medicines. Recently, people have begun to explore the possibility of using “refined biomass” as starting materials for chemical conversions leading to novel high value-in-use products. Over the past two decades, the cost of renewable biomass materials has decreased to a point where many are competitive with those derived from petroleum. In addition, many materials that cannot be produced simply from petroleum feedstocks are potentially available from biomass or refined biomass. Many of these unique, highly functionalized, molecules would be expected to yield products unlike any produced by current chemical processes. “Refined biomass” is purified chemical compounds derived from the first or second round of plant biomass processing. Examples of such materials include cellulose, sucrose, glucose, fructose, sorbitol, erythritol, and various vegetable oils.
A particularly useful class of refined biomass is that of aldaric acids. Aldaric acids, also known as saccharic acids, are diacids derived from naturally occurring sugars. When aldoses are exposed to strong oxidizing agents, such as nitric acid, both the aldehydic carbon atom and the carbon bearing the primary hydroxyl group are oxidized to carboxyl groups. An attractive feature of these aldaric acids includes the use of very inexpensive sugar based feedstocks, which provide low raw material costs and ultimately could provide low polymer costs if the proper oxidation processes are found. Also, the high functional density, of these aldaric acids, provides unique, high value opportunities, which are completely unattainable at a reasonable cost from petroleum-based feedstocks.
Aldaric acid derivatives, because of their high functionality, are potentially valuable monomers and crosslinking agents.
Diaminoaldaramides, dihydroxyaldaramides, bis(alkoxycarbonylalkyl)aldaramides, and bis(carboxyalkyl)aldaramides are examples of monomers and crosslinking agents that could be prepared. No simple method exists for the preparation of all of these. Hoagland (Carbohydrate Res., 98 (1981) 203-208) studied the kinetics of the aminolysis of diethyl galactarate. This procedure would not be expected to produce the same results using the equivalent lactone or dilactone. Reaction of a polyhydroxy diester or dilactone with a diamine has the potential to produce oligomers and polymer and to undergo various side reactions. Gorman and Folk (J. Biol. Chem. 1980, 255, 1175-1180) employ a 4-step sequence to protect one end of ethylenediamine, react with diethyl tartrate, and deprotect. It would be expected that an aminoester would not react with another ester without competing reaction with itself to form oligopeptides. Pecanha, et al. (WO02/42412) employ a four-step sequence to protect the hydroxyl groups of tartaric acid, activate the carboxyl groups as acyl chloride groups, react with an amino acid ester, and deprotect.
Applicants have discovered new difunctional aldaramides that can be used as monomers or polymer crosslinkers, and processes for preparing the aldaramides.